Many embodiments of conventional flashlights employ parabolic reflectors as part of their light source to outwardly direct the light from a bulb contained therein outward toward an object that is wished to be illuminated. When the bulb is located at the focus of the paraboloid, the light rays leaving the bulb, and subsequently impacting on the surface of the reflector, will travel the same distance as they emerge parallel to axis. This arrangement results in a bright and concentrated spot beam.
Conventional flashlights are also capable of forming a broader beam by moving the light bulb relative to the paraboloid so that the bulb is no longer at the focus. The result of moving the bulb from the focus is that the light rays leaving the bulb reflect off the paraboloid surface and emerge diverging from the central axis. The broader beam formed in this manner has several deficiencies. First, the broader beam appears to be less bright by at least the increase in the beam area over the area of the spot. In addition, the broader beam has an unilluminated spot at its center. This center dark area is caused by light rays originating at a location other than the focus of the parabolic reflector. These deficiencies with the resultant broad beam creates a non-ideal illumination pattern on objects that are being viewed.
Prior attempts to eliminate unilluminated portions of a flashlight's beam of light have included flashlights constructed with complex reflectors including multiple parabola, flashlights constructed with multiple light sources and control circuitry, and flashlights constructed with a light source which moves within the reflector. Examples of flashlights which employ the above techniques are described with two patents issued to Ellison (U.S. Pat. No. 4,984,140 and U.S. Pat. No. 5,367,446). Undue complexity of said flashlight designs leads to unacceptably high manufacturing costs and lead to issues of reliability associated with their operation.